The R107 Reception Set

[Replicaright]

Hi All
I obtained an R107 about 20 years ago needing the 2 x 8mfd replacing, and it has worked very well until recently, when it started to lose performance. I decided to replace the decoupling caps 0.1-0.01-0.05 (using 0.047) @ 630 vw.This has revitalised the set for about 20 minutes, but upon switching the set back on again it is silent. The only sound from the speaker is a click from operating the audio filter switch. All valves light up and the power light indicator is on. On testing the voltages on the small front panel all is OK except 1B, which shows no reading (this is V1b the frequency changer ARP34) I have swapped the valve with another one from the set but still no reading. Also I can feel a tingling from the set handles. Any ideas on the problem?
regards Jon

[Skywave]

Can you state which electrode (or valve socket pin number) of the ARP34 freq. changer that has no voltage, please ? (I suggest you measure the voltages actually at the valve, rather than rely on the indicated reading on the small front panel.) This info. will narrow the field of possibilities and thus help us help you.

Al.

[short wave]

If measuring voltages with respect to chassis and tag board on front of set then i would suspect the following
R6d o/c
R4C o/c
C11A s/c
hope this is a starter. As Sky wave recommended can you take some measurements on the valve bases?
GOOD info here
http://bama.edebris.com/manuals/britmil/r107
regards S-W

[Replicaright]

Hi
Thanks for the replies experts. However novice error has loomed large on this one. I had mistakenly connected C10B to Earth instead of going to VR2. Amazing that this simple error renders the whole set dead. I am now going to add a couple of spare valves for the future. Who is doing valves these days-I used to get them from Centre Electronics, Yardley, Birmingham.
Regards Jon

[short wave]

Did you also get rid of the "tingles?" Make sure your R107 is earthed if it isn't I suspect one of the input caps is leaky (the one that is connected to your live supply).

Regards, S-W.

[g4aaw pete]

Originally Posted by Replicaright

Who is doing valves these days

I would have said ebay.
As the line-up consists of EF39s, EBC33s & a 6X5G, one of each would probably be about £30

Regards
Pete

As the line-up consists of EF39s, EBC33s & a 6X5G, one of each would probably be about £30

And not really needed, valves hardly ever fail.

[G6Tanuki]

If you know where to get them, the valves are around a fiver a time.

[Radio Wrangler]

Fix the tingles first.

You may be using/working on a set with a broken earth connection, and we wouldn't want to lose you so early in a promising career as a new restorer

David

[Sean Williams]

The case handles and chassis being live is a very common fault on this set - the two mains filter caps that connect to live and netural down to earth will be electrically leaky - either remove them completely, or replace with suitably rated components.

[Replicaright]

Hi.

Re R107 input filter capacitors. I have removed the two original capacitors and both are clearly stamped 1.0 mfd 600vwkg. The online manual on the forum indicates 0.001mfd and the original handbook that came with the set indicates 1000pf. These are for C23A B.

Which is correct?
Regards Jon

[Replicaright]

Hi all.

Seem to have removed the DC capacitors instead. I will replace those. I can now see the AC caps -2 x Hunts piggyback with a common black wire earth. The two blue wires from the Hunts go to thru posts on a coil. Can I connect to either end of the thru posts? It would be easier.
regards Jon

[Station X]

Originally Posted by Replicaright

Hi.

Re R107 input filter capacitors. I have removed the two original capacitors and both are clearly stamped 1.0 mfd 600vwkg. The online manual on the forum indicates 0.001mfd and the original handbook that came with the set indicates 1000pf. These are for C23A B.

Which is correct?
Regards Jon

0.001uF and 1000pF are the same thing.

[Replicaright]

Hi All
R107 now has no tingling feeling anymore and on RT works well-however if I turn the RF Gain to maximum 10 there are loud whistles over the received stations.Should I not have this on maximum-the whistles go when turned down to 9 on the RF gain dial.Or do I have another problem?
regards Jon

[Sean Williams]

check the metallising on all of the EF39 and EBC33 valves - if this is not grounded these sets take off and oscillate like mad!

[Replicaright]

Hi All
The metallising on the valves looks sound and I have tested for continuity from the metallising to pin 1 on all valves which seems OK.However I tried wrapping all valves (not the rectifier) with cooking foil and this has removed the whistling noises.
regards Jon